Nail terminology

Author: Dr Amanda Oakley, Clinical Associate Professor, Waikato Clinical School, 1997.

This page outlines the terms used by dermatologists to describe diseases of the fingernails and toenails.

Abnormalities of the nail plate surface

Nail plate abnormalities are often due to inflammatory conditions affecting the matrix or nail bed. Specific diagnoses may be made from characteristic appearances.

Pitting may be a sign of eczema, psoriasis (haphazard: upper image), alopecia areata (regular: lower image)
Nail psoriasis pitting
  Alopecia areata nail pitting
Transverse ridging
Transverse ridging may be a sign of eczema (top image), paronychia (lower image), psoriasis, parakeratosis pustulosa
Nail ridges due to eczema
  Nail ridging due to eczema
Beau line
Beau line is a transverse depression affecting all nails, due to acute systemic illness stopping nail growth.
Beau line of nail
Onychorrhexis is longitudinal ridging. Consider aging (top image), lichen planus (middle image), psoriasis, fungal nail infection, Darier (bottom image) or a habit of picking
Longitudinal nail ridging
  Lichen planus of nails
  Darier nail disease
Longitudinal groove
Median canaliform dystrophy
Median canaliform dystrophy is due to myxoid cyst (image) or wart
Nail groove due to myxoid cyst
Median nail dystrophy
Feathered longitudinal ridge
2nd image: © Dr Ph Abimelec – dermatologue
Median canliform dystrophy
  Median canaliform dystrophy
Onychogryphosis is a thick hard curved nail plate in the shape of a ram's horn.
due to aging (image), psoriasis or trauma
Onychauxis is a thick nail due to psoriasis (top image), trauma or fungal nail infection (bottom image)
Psoriatic nail dystrophy
  Fungal nail infection
Angel-wing deformity
Angel-wing deformity describes nail plate thinning due to lichen planus
Nail plate crumbling
Typical of psoriasis (top image) and fungal nail infection (bottom image)
Nail dystrophy due to psoriasis
  Nail dystrophy due to onychomycosis
Onychoschizia is distal lamellar splitting/brittle nails due to water/detergent damage
Nail splitting: onychoschizia
Longitudinal splitting
An extension of ridging seen in psoriasis, fungal nail infection (top image) or lichen planus (bottom image)
Bottom image ©R Baran
Longitudinal splitting of nail
  Nail splitting due to lichen planus
Distal notching
Consider Darier (image) and lichen planus
Darier nail disease
Trachyonychia means rough nails. If all nails affected, known as Twenty Nail Dystrophy, probably due to lichen planus
Twenty nail dystrophy trachyonychia
Consider trauma or malignant tumour e.g. SCC or melanoma (image)
Melanoma of nail
Acrylic nails
Decorative cosmetic
Acrylic nail
  Nail cosmetics

Nail discolouration

Distinguish a discoloured nail bed from a discoloured nail plate.

Yellow nail syndrome
Yellow or green nails due to lymphatic obstruction in cardiopulmonary disease
Yellow nails
  Yellow nails
Green nails
Pseudomonas/candida infection
Candida nail infection
Yellow nails
Due to fungal nail infection
Fungal nail infection
Lateral yellow streak
Due to dermatophyte onychomycosis
Yellow nails
Due to psoriasis
Nail psoriasis
Oil drop or salmon patch
Due to psoriasis: orange or brown streak proximal to onycholysis
Psoriatic nail dystrophy
Brown nails
Consider staining (nicotine, potassium permanganate, nail varnish) and chemotherapy. Illustrated are staining from podophyllin (top image) and streaks due to oral hydroxyurea (bottom image).
Nail staining
  Nail discoloration due to hydroxyurea
White nails and adjacent skin
White nail due to vitiligo
White nails. Consider hypoalbuminaemia or chronic renal failure. May be familial. Transverse leukonychia, or multiple parallel white lines, are thought to be due to manicuring but may also arise in association with Beau's lines.
White streaks
Traumatic e.g. manicuring
White spots on nail
  White spots on nails
  Transverse leukonychia
White or yellow distal nail, lifted off. Consider idiopathic causes (top image), trauma, psoriasis (second image), thyrotoxicosis, irritant and allergic contact dermatitis, fungal nail infection (candida: third image), drug photosensitivity (especially tetracycline: bottom image; and psoralens)
  Psoriatic onycholysis
  Nail candidiasis
White spotting
Due to superficial white onychomycosis
Half-and-half nails
Seen in renal failure. White proximal nail, brown distal nail
Half and half nail
Terry's nails
Seen in liver cirrhosis. White proximal nail, reddened distal nail
Terry nail
  Terry nail
Mee's lines
Partial leukonychia due to arsenic intoxication or systemic disease
Muehrcke's lines
Double band of leukonychia in renal disease
Muehrcke nail
Red lunula Red lunula
Red longitudinal streak
Erythronychia due to onychopapilloma
Red and white streaks
Seen in Darier disease
Darer nail erythronychia
Red tender area
Consider glomus tumour
1st Image ©R Baran
2nd image © Dr Ph Abimelec – dermatologue
Glomus tumour of nail
  Glomus Tumour
Blue nail
Consider drugs (all nails affected), in this case minocycline
Blue nails due to minocycline
Red/purple streak
Splinter haemorrhage
Splinter haemorrhages
Purple/black nail
Haematoma (blood clot)
Subungual haematoma
Black nail
Pseudomonas infection
Black nails with pseudomonas infection
Melanonychia is a brown/black band due to benign melanocytic naevus.
Multiple brown linear streaks
Also called longitudinal melanonychia. May be of racial origin or Laugier-Hunziker Syndrome. Rarely due to drug (azidothymidine, tetracycline), endocrine disorders or Peutz-Jeghers syndrome.
Multiple melanonychia
Expanding variable colour/shaped streak
Consider melanoma
Bottom image ©R Baran
Nail melanoma
  Subungual melanoma

Abnormalities of the cuticle and nail fold

The cuticle is an area of keratin joining the skin of the posterior nail fold to the nail plate. Loss of cuticle reuslts in paronychia.

Ragged cuticles
Connective tissue disease, parakeratosis pustulosa
Ragged cuticles
Hang nail
Trauma (biting)
Hang nail
Nail fold telangiectases
Connective tissue disease e.g. lupus erythematosus
Nail fold telangiectasia
Distal digital infarcts
Nail infarction
Subungual hyperkeratosis
Scaling under hyponychium. Typical of psoriasis (top image) and onychomycosis but also arises in crusted scabies (bottom image)
subungual hyperkeratosis
  Crusted scabies with scaling under nails
A pterygium is a wing of extra tissue. In a nail, it is due to scarring in the matrix. Characteristic of lichen planus (image) but may occur in Stevens-Johnson syndrome and from trauma
Pterygium of nail due to lichen planus
Acute paronychia
Staphylococcus aureus
Acute paronychia
Acute paronychia
Herpes simplex
Acute herpetic paronychia
Chronic paronychia
Candida albicans or pseudomonas
Chronic paronychia
Acrodermatitis continua of Hallopeau
Acrodermatitis continua of Hallopeau is a form of severe psoriasis
Acrodermatitis continua
Embedding of the nail into the nail fold and subsequent inflammation.

Abnormalities of nail shape

Osteoid osteoma (bone tumour)
©R Baran
Nail enlargement due to osteoma
Uncut nail
Resorption of distal phalanx
Overcurvature of nail
Due to hypertrophic osteoarthropathy (image) or thryoid disease (acropachy)
Clubbing of nail
Thin spoon-shaped nail can be seen in normal children and adults. It is also associated with iron deficiency anaemia, diabetes, protein deficiency, connective tissue disease, nail exposure to solvents and and acitretin treatment
©R Suhonen
Wedge-shaped nails
Pincer nail
Sometimes familial or associated with psoriasis
Pincer nail deformity
In-growing nail with granuloma formation. Aggravated by retinoids such as isotretinoin or acitretin
Ingrowing nail

Loss of nails

Without scarring
Usually traumatic eg nail biting; in children parakeratosis pustulosa
Nail biting
  Bitten nail
Due to tumour (upper image) or erosive lichen planus (bottom image)
Bottom image © R Baran
Nail loss due to melanoma
  Nail loss due to lichen planus
Nail shedding may follow hand, foot and mouth disease, Stevens-Johnson syndrome / toxic epidermal necrolysis, or other acute and severe systemic illness
Nail shedding due to lichen planus
Nail patella syndrome
© Dr Ph Abimelec – dermatologue
Nail dystrophy in nail patella syndrome

Lesions around nails

Common skin lesions around nails include:

Viral warts Periungual warts
Melanocytic naevus Melanonychia
Subungual melanoma Subungual melanoma
Squamous cell carcinoma or keratoacanthoma (image)
©R Baran
Subungual squamous cell carcinoma
Corn Corn
Subungual fibroma
2nd image © Dr Ph Abimelec – dermatologue
Periungual fibroma
  Subungual fibroma
Inclusion cyst
© Dr Ph Abimelec – dermatologue
Inclusion epidermal cyst
© Dr Ph Abimelec – dermatologue
Subungual exostosis Subungual exostosis
Giant cell tumour of tendon sheath
© Dr Ph Abimelec – dermatologue
Giant cell tumour of tendon sheath
Myxoid cyst Myxoid cyst
Pyogenic granuloma Periunguagl pyogenic granuloma

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